BACKGROUND AND AIMS There is increased evidence that partial nitrate (NO3-) nutrition (PNN) improves growth of rice (Oryza sativa), although the crop prefers ammonium (NH4+) to NO3- nutrition. It is not known whether the response to NO3- supply is related to nitrogen (N) use efficiency (NUE) in rice cultivars. Methods Solution culture experiments were carried out to study the response of two ri...

The asymmetric unit of the title compound, NH4 (+)·C11H14N6O7P(-)·0.5H2O, contains one 3'-azido-3'-de-oxy-thymidine-5'amino-carbonyl-phospho-nate (ACP-AZT) anion, half of an NH4 (+) cation lying on a twofold rotation axis and in another position, occupied with equal probabilities of 0.5, an NH4 (+) cation and a water mol-ecule. The amide group of the ACP-AZT anion is disordered (occupancy ratio...

Pathways of ammonium (NH4 (+)) removal were investigated using the stable isotope approach in constructed wetlands (CWs). We investigated and compared several types of CWs: planted horizontal subsurface flow (HSSF), unplanted HSSF, and floating plant root mat (FPRM), including spatial and seasonal variations. Plant presence was the key factor influencing efficiency of NH4 (+) removal in all CWs...

Soils and vegetation were analyzed in 20 lodgepole pine (Pinus contorta) forest stands, varying in age from 50 to 350 years, that had initiated following stand-replacing fire. Our goal was to determine how nitrogen availability (NH4 –N) and microbial community composition varied with stand age-class and to determine whether differences could be explained by canopy, soil, or understory character...

Adsorption and desorption of phosphorus (P) and nitrogen (N) by stalk residues may influence the concentrations of P and N in runoff. A laboratory study was conducted to measure the effects of P and N constituents in solution on adsorption and desorption of P and N by corn, soybean, and wheat stalk residues. Experimental variables included type of stalk material (corn, soybean, and wheat), inor...

a biofilm sequencing batch reactor with a volume of 1.42 m3, nylon nets providing a 4,140 m2/m3 support area for biofilms and an automated operation with 8 hour cycles was studied. the duration of the experiment was 135 days. removal efficiencies e≥ 80% were obtained for carbonaceous matter, producing an effluent with 31±26.8 mg/l of filtered cod, 7±3.6 mg/l of bod5 and 12±3.2 mg/l of toc. the ...

Removal efficiency of COD, NH4-N and PO4-P and NO3-N in five step SBR processes is widely influenced by hydraulic retention time of Anaerobic/Anoxic/Aerobic/Anoxic/Aerobic step of this system where the hydraulic retention time in each step is influence directly on removal efficiency of this system therefore the operator of this system cannot control on this system without experience or a contro...

The leachates generated at Hong Kong landfill sites contain high strength of ammonium-nitrogen (NH4+-N) over 3,000 mg l(-1) and are generally inhibitive to most biological treatment processes. To remove the NH4+-N from the landfill leachates and also recover the nitrogen as a struvite fertilizer, a lab-scale study was performed to investigate the feasibility of NH4+-N removal and struvite cryst...

The influence of different N sources on the growth of maté (Ilex paragurariensis St.Hil.) seedlings grown in greenhouse was studied. All seedlings received a base fertilization of 10 mg N.kg soil as NH4NO3, 60 mg P2O5.and 40 mg K2O.kg -1 soil as KH2PO4 15 days before treatments application. Treatments were as follow: Control, with no extra N added; Urea = 100 mg N.kg soil as Urea; NO3 = 100 mg ...